Electrical water heating unit



Sep%. 24, 1935. G. L. COLBIE ELECTRICAL WATER HEATING UNIT Filed Sept. 25, 1955 lNVENTOR Gus L. Co/bz'e ATTORNEY Patented Sept. 24, 1935 UNITED STATES PATENT OFFICE ELECTRICAL WATER HEATING UNIT Gus L. Colbie, Brooklyn, N. Y.

Application September 25, 1933, Serial No. 690,803

8 Claims.

This invention relates generally to electrical apparatus for efiiciently heating water, but is designed more specifically for use in water tube boilers. This application constitutes a continuation in part of my prior application Serial No.

562,931, filed September 15, 1931, which will be issued as Patent No. 1,928,446 on September 26, 1933.

The objects of this invention, among others, are to produce a simple, rugged form of heating member which may be made in standard forms and quickly assembled for insertion in a watertight envelope, the heating unit the-n resulting being adapted for convenient insertion in any form of water tube steam boiler or water heater, or for quick removal therefrom without disturbing other members or units; the production of the greatest possible efiiciency in heat transference from resistor to water; the creation of a rapid circulation of air in said unit from resistor to envelope walls and back again; the avoidance of short circuits and circuit grounding; the utmost freedom for relative expansion and contraction of the parts, etc.

The best form of apparatus embodying my invention, at present known to me, is illustrated in the accompanying sheet of drawing in which:

Fig. 1 is a vertical section on lines 1-! of Fig. 3 with parts broken away showing the heater element as installed in the particular form of water tube boiler shown in my said Patent No. 1,928,446.

Fig. 2 is a cross section on line 2--2 of Fig. 1, and

Fig. 3 is a cross section on line 33 of Fig. 1.

Throughout the drawing like reference charac- Y ters indicate like parts. In the preferred embodiment here shown the generator comprises a plurality of tubular members or water jackets, one of which is shown at 12, preferably arranged vertically and joined at their upper ends 14 to a series of steam headers, one of which is shown at I6, and at their lower ends l8 to a corresponding series of water headers, one of which is shown at 20. To retain the tube 12 within the headers 16 and 20, I roll the ends and force annular ribs thereon into annular recesses 13 in the header openings 15 to form water and steam-tight joints. The rolling operation is performed by means of a tool which is adapted to be inserted through the upper and lower header openings, the upper openings being subsequently closed by the heating unit mounting member to be described hereafter and the lower openings being subsequently closed by caps 11 which are inserted through the water inlet opening IS in the header 20.

Within each water jacket I2 is suspended a centrally disposed standardized heating unit generally indicated at 22, which comprises an electrical heating member generally indicated at 23, contained within a water-tight and steam-tight envelope 24, the walls of which are preferably corrugated longitudinally as clearly shown in Figs. 2 and 3.

The said envelope 24 is closed at its lower end and has an outwardly flared flange 26 at its upper end, which fits over an annular internal shoulder 28, in an opening 25, in the upper wall of the steam header 16. Flat spring members 30 welded to the inside of the tube [2 at 32, are adapted to make contact with the lower surface of the envelope 24 to retain same in spaced relation within the water jacket and leave the lower end of the envelope 24 free for expansion and contraction relative to tube 12, in both radial and axial direction.

The electrical heating element 23 comprises a continuous strand of resistance wire 34 of large cross section which is passed through spacer discs 36 of insulating material, to provide several vertically disposed lengths in a fixed, spaced relation, one with another.

In assembling the heating member 23, two halves of a sleeve or casing 38, having internal 3O circumferential ribs 40 or the like, are placed around a plurality of the discs 36, said discs being confined between the ribs 40. After assembling, the sleeve 33 may be welded at various points along the joints as indicated at 42, and two rings 44-44 are placed around the sleeve near the top thereof and welded thereto, leaving a space between to accommodate a split insulating collar 46. Since the two halves of the casing 38 are slightly separated, as indicated in Figs. 2 and 3, open spaces will be left between them, through which heated air can flow from the resistor 34 to the inner surface of the envelope 24; thence by conduction the heat will pass to the water or steam on the other side of such envelope wall. Other openings may be provided in the casing 38 if desired.

Within the lower end of the envelope 24 is a centering block 48 of insulating material, having 50 a recess 50 in its upper face adapted to receive the lower end of the casing 38, and to maintain same in a fixed spaced relation to the envelope 24.

A space is left between the bottom of the casing 38 and the bottom of recess 50 to allow for longitudinal expansion and contraction of the said casing relative to envelope 24.

To assemble an entire heating unit the envelope 24 is inserted into a water tube or jacket l2 through one of the openings 25 in the upper wall of the steam header 16. The flange 26 around the open, upper end of such envelope 24 is seated against suitable packing 21, resting on shoulder 28. A screw threaded collar 52, having an internal recess 54, is screwed into an internally threaded upper portion 56 of the header wall forming each opening 25, the lower surface of said collar being brought into clamping engagement with the flange 26, on the shell or envelope 24. A portion of said screw threaded collar 52 projects above the top of the steam header l6.

After the electrical resistance member is assembled within the casing 38, as previously described, two halves of the split insulating collar 46 are placed around the upper portion of the sleeve 38, between the rings 64-44 and the main portion thereof is then inserted in the shell or envelope 24. The lower end of the casing 38 is placed in the recess 50, within the insulating block 48, and the split insulating collar 46 is fitted into the recess 54, in the threaded collar 52. The top of the said collar 46 projects slightly above the top of the threaded collar 52 when first placed therein. To retain this assembly within the envelope 24 an internally threaded annular cap 60 is screwed onto the projecting portion of the threaded collar, said cap being provided with an inwardly extending flange 62, which is adapted to be brought into contact with the upper surface of the projecting portion of the split insulating collar 46, and compress the same when such cap is screwed down tight.

The annular threaded collar 52 and its con tained insulating filler elements, the split ring 54 and upper disc 36, when thus assembled, together form a removable closure for the open end of the envelope 24, and also serve as means of supporting that end of the electrical heating assembly, including resistor 35, spacing discs 36 and their containing casing 38.

The ends of the resistance wire 34 are extended upwardly, as shown at GI, and on their ends internally threaded lugs 63 are adapted to be screwed or welded, said lugs having threaded shanks 65 which project up through an insulating cap 61 resting on the upper ring 44. Straps of copper 1| or any other form of connection may be used to connect the units together, perforated ends of the straps being placed over the ends of shanks 65 and secured thereon by nuts 13.

It will be observed from the foregoing description of the standardized heating unit that an interchangeable unit has been developed which can be inserted in any suitable boiler construction, and can be transferred from, one to another portion of any multi-cell boiler (as is shown in my above noted patent). It will also be observed that the electrical heating assembly or the resistor, a resistor supports and the closure carrying these elements, forms a standardized unit which can be used with any envelope 24.

The features of construction of the boiler shown in the drawing in addition to those already described comprise a feed water supply tube 64 having a branch 65 for each water header terminating in a header plate 68 which is bolted to lower head 2|] over the opening IS in the latter. A take-off conduit 16 leads from asimilar header plate 18, one of which is bolted to each upper, or

steam, header l6 over a suitable opening in a side wall of the latter.

Making the envelope 24 for the heater member of corrugated cross section, as shown, adds matcrially to the heat absorbing and radiating surfaces thereof, and so facilitates the transfer of heat from the resistor 34 to the water in tube 12, thus permitting the resistor to be operated at a lower temperature for a given steam output, or causing an increased steam production it the resistor is maintained at the maximum safe temperature.

Various changes could be made in the details of construction and operation hereinbefore described as embodying the preferred form of my invention without departing from the underlying novel principles thereof so long as such modified elements cooperate in substantially the way herein described to produce the beneficial results herein pointed out, and come within the definitions of the appended claims.

Having described my invention, I claim:

1. An electrical heating unit especially suitable "for use in steam boilers comprising, in combination, an elongated steamtight envelope closed at one end and having thin walls of corrugated cross section in planes extending transversely of said envelope, a resistor extending longitudinally of the interior of said envelope, and electrical insulating means for supporting the free ends of said resistor mounted on and closing the otherwise open end of said envelope, together with skeleton insulating means for supporting the resistor within said envelope spaced away considerable distances from the corrugated walls thereof; whereby free access to the inner surfaces of said corrugated walls is afforded for currents of air heated by said resistor when current is passed therethrough.

2. An electrical heating unit adapted to be inserted in a boiler, which unit comprises, in combination, an elongated, steamtlght envelope closed at one end, supporting means adapted to be placed in the open end of said envelope comprising an insulating section, a casing supported in said means and projecting into said envelope but spaced away from the walls thereof, and a resistor located in said casing but spaced away therefrom and having its terminals projecting through and supported in said insulating section of said supporting means.

3. A combination such as defined in claim 2 in which said casing has openings in its side walls for circulation therethrough of heated air.

4. A structure such as defined in claim 2 combined with a centrally recessed block of insulating material located in the closed end of the envelope, in which recess the other end of said casing nests.

5. A combination such as defined in claim 2 in which said casing comprises two semi-cylindrical portions held together by two spaced-apart, external rings, and in which said supporting means comprises a ring of insulating material held between said first mentioned rings.

6. An electrical heating unit adapted to be inserted in a cylindrical envelope, which unit comprises a thin metal cylinder having pairs of inwardly projecting annular ribs formed in its walls, a perforated insulating disc located between, and held in place by the members of each pair of ribs, and a resistor element supported by said discs within said cylinder.

7. A combination such as defined in claim 6 in which said metal cylinder is formed in semicylindrical halves held together but spaced apart slightly.

8. A casing for supporting an electrical-heating element mounting comprising two semicylindrical halves of sheet metal each having a. series of internal semi-annular ribs rolled therein at points spaced apart longitudinally of said half casing and adapted to support; an insulating disk nested between any two adjacent members of such rib series when the semi-cylindrical halves are assembled for supporting the electrical heating element, when encased within the halves, and means for holding the casing halves together.

GUS L. COLBIE. 

